Thermology
Electrical engineering may or may not include
electronic engineering. Where a distinction is made, usually outside of the United States, electrical engineering is considered to deal with the problems associated with large-scale electrical systems such as
power transmission and
motor control, whereas electronic engineering deals with the study of small-scale electronic systems including
computers and
integrated circuits.Alternatively, electrical engineers are usually concerned with using electricity to transmit energy, while electronic engineers are concerned with using electricity to transmit information.
History
Electricity has been a subject of scientific interest since at least the early 17th century. The first electrical engineer was probably
William Gilbert who designed the
versorium: a device that detected the presence of statically charged objects. He was also the first to draw a clear distinction between magnetism and static electricity and is credited with establishing the term electricity.
In 1775
Alessandro Volta's scientific experimentations devised the
electrophorus, a device that produced a static electric charge, and by 1800 Volta developed the voltaic pile, a forerunner of the electric battery.
During this period, the work concerning electrical engineering increased dramatically. In 1882,
Edison switched on the world's first large-scale electrical supply network that provided 110 volts
direct current to fifty-nine customers in lower Manhattan. In 1884
Sir Charles Parsons invented the
steam turbine which today generates about 80 percent of the
electric power in the world using a variety of heat sources. In 1887,
Nikola Tesla filed a number of patents related to a competing form of power distribution known as
alternating current. In the following years a bitter rivalry between Tesla and Edison, known as the "
War of Currents", took place over the preferred method of distribution. AC eventually replaced DC for generation and power distribution, enormously extending the range and improving the safety and efficiency of power distribution.
The efforts of the two did much to further electrical engineering—Tesla's work on
induction motors and
polyphase systems influenced the field for years to come, while Edison's work on telegraphy and his development of the
stock ticker proved lucrative for his company, which ultimately became
General Electric. However, by the end of the 19th century, other key figures in the progress of electrical engineering were beginning to emerge.
Modern developments
During the
development of radio, many scientists and
inventors contributed to
radio technology and electronics. In his classic
UHF experiments of 1888,
Heinrich Hertz transmitted (via a
spark-gap transmitter) and detected
radio waves using electrical equipment. In 1895, Nikola Tesla was able to detect signals from the transmissions of his New York lab at West Point (a distance of 80.4 km / 49.95 miles).
In 1897,
Karl Ferdinand Braun introduced the
cathode ray tube as part of an
oscilloscope, a crucial enabling technology for
electronic television.
John Fleming invented the first radio tube, the
diode, in 1904. Two years later,
Robert von Lieben and
Lee De Forest independently developed the amplifier tube, called the
triode.
In 1895,
Guglielmo Marconi furthered the art of hertzian wireless methods. Early on, he sent wireless signals over a distance of one and a half miles. In December 1901, he sent wireless waves that were not affected by the curvature of the Earth. Marconi later transmitted the wireless signals across the Atlantic between Poldhu, Cornwall, and St. John's, Newfoundland, a distance of 2,100 miles (3,400 km).
In 1920
Albert Hull developed the
magnetron which would eventually lead to the development of the
microwave oven in 1946 by
Percy Spencer.
In 1934 the British military began to make strides toward
radar (which also uses the magnetron) under the direction of Dr Wimperis, culminating in the operation of the first radar station at
Bawdsey in August 1936.
In 1941
Konrad Zuse presented the
Z3, the world's first fully functional and programmable computer.
In 1946 the
ENIAC (Electronic Numerical Integrator and Computer) of
John Presper Eckert and
John Mauchly followed, beginning the computing era. The arithmetic performance of these machines allowed engineers to develop completely new technologies and achieve new objectives, including the
Apollo missions and the
NASA moon landing.
The invention of the transistor in 1947 by William B. Shockley, John Bardeen and Walter Brattain opened the door for more compact devices and led to the development of the
integrated circuit in 1958 by Jack Kilby and independently in 1959 by Robert Noyce.Starting in 1968, Ted Hoff and a team at Intel invented the first commercial microprocessor, which presaged the personal computer. The Intel 4004 was a 4-bit processor released in 1971, but in 1973 the Intel 8080, an 8-bit processor, made the first personal computer, the Altair 8800, possible.
Subdiciplene
Electrical engineering has many sub-disciplines, the most popular of which are listed below. Although there are electrical engineers who focus exclusively on one of these sub-disciplines, many deal with a combination of them. Sometimes certain fields, such as electronic engineering and computer engineering, are considered separate disciplines in their own right.
Power
Power engineering deals with the
generation,
transmission and
distribution of
electricity as well as the design of a range of related devices. These include
transformers,
electric generators,
electric motors, high voltage engineering and
power electronics. In many regions of the world, governments maintain an electrical network called a
power grid that connects a variety of generators together with users of their energy. Users purchase electrical energy from the grid, avoiding the costly exercise of having to generate their own. Power engineers may work on the design and maintenance of the power grid as well as the power systems that connect to it. Such systems are called
on-grid power systems and may supply the grid with additional power, draw power from the grid or do both. Power engineers may also work on systems that do not connect to the grid, called
off-grid power systems, which in some cases are preferable to on-grid systems. The future includes Satellite controlled power systems, with feedback in real time to prevent power surges and prevent blackouts.
Control
Electronics
Prior to the second world war, the subject was commonly known as
radio engineering and basically was restricted to aspects of communications and
radar,
commercial radio and
early television. Later, in post war years, as consumer devices began to be developed, the field grew to include modern television, audio systems,
computers and
microprocessors. In the mid to late 1950s, the term
radio engineering gradually gave way to the name
electronic engineering.
Before the invention of the
integrated circuit in 1959, electronic circuits were constructed from discrete components that could be manipulated by humans. These discrete circuits consumed much space and
power and were limited in speed, although they are still common in some applications. By contrast,
integrated circuits packed a large number—often millions—of tiny electrical components, mainly
transistors, into a small chip around the size of a
coin. This allowed for the powerful
computers and other electronic devices we see today.
Microelectronics
Microelectronic components are created by chemically fabricating wafers of semiconductors such as silicon (at higher frequencies,
compound semiconductors like gallium arsenide and indium phosphide) to obtain the desired transport of electronic charge and control of current. The field of microelectronics involves a significant amount of chemistry and material science and requires the electronic engineer working in the field to have a very good working knowledge of the effects of
quantum mechanics.
Signal processing
Signal Processing is a very mathematically oriented and intensive area forming the core of
Digital Signal Processing (
DSP) and it is rapidly expanding with new applications in every field of electrical engineering such as communications, control, radar, TV/Audio/Video engineering, power electronics and bio-medical engineering as many already existing analog systems are replaced with their digital counterparts.
Although in the classical era,
analog signal processing only provided a mathematical description of a system to be designed, which is actually implemented by the
analog hardware engineers, Digital Signal Processing both provides a mathematical description of the systems to be designed and also actually implements them (either by software programming or by hardware embedding) without much dependency on hardware issues, which exponentiates the importance and success of DSP engineering.
The deep and strong relations between signals and the information they carry makes signal processing equivalent of information processing. Which is the reason why the field finds so many diversified applications. DSP processor ICs are found in every type of modern electronic systems and products including,
SDTV |
HDTV sets, radios and mobile communication devices,
Hi-Fi audio equipments,
Dolby noise reduction algorithms,
GSM mobile phones,
mp3 multimedia players, camcorders and digital cameras, automobile control systems,
noise cancelling headphones, digital
spectrum analyzers, intelligent missile guidance,
radar,
GPS based cruise control systems and all kinds of
image processing,
video processing,
audio processing and
speech processing systems.
Telecommunications
Once the transmission characteristics of a system are determined, telecommunication engineers design the
transmitters and
receivers needed for such systems. These two are sometimes combined to form a two-way communication device known as a
transceiver. A key consideration in the design of transmitters is their
power consumption as this is closely related to their
signal strength. If the signal strength of a transmitter is insufficient the signal's information will be corrupted by
noise.
Instrumentation
Often instrumentation is not used by itself, but instead as the
sensors of larger electrical systems. For example, a thermocouple might be used to help ensure a furnace's temperature remains constant. For this reason, instrumentation engineering is often viewed as the counterpart of control engineering.
Computers
souce : wikipedia